Service manual

CIO DESCRIPTION
29
3.3.1.1. Conversion formulas for voltage measurement
U = 215 * AD / 1024 [0.1 V]
AD = 1024 * U / 215
Whereas: AD…analogue/digital converter value
U …voltage measured
3.3.2.
Measuring internal CDA70 temperature
The temperature measuring inside the CDA70 unit is performed to secure correct
function of the radio module. If the temperature exceeds the set decision level, the VF module
is disconnected from the supply voltage, because its correct function is no longer guaranteed
above such temperature. At the same time, it is thus protected against damage due to thermal
overload.
Signal
name
Measuring
range [°C]
Resolution
[bit]
Sampling
[msec]
Average
from
samples
Hysteresis Control level
TEP -40 to 100 10 5000 16 2
o
C Optional
3.3.2.1. Conversion formulas for temperature measurement
T = 625 * AD/128 – 2730 [0.1
o
C]
AD = 128 * (T + 2730) / 625
Whereas: AD…analogue/digital converter value
T …temperature measured
3.3.3.
Measuring DSR output signal level
On CDA70 side, DSR signals on individual user interfaces are output signals. They are
not internally controlled. Individual signals are connected via 560 ohms resistors to the 12V
supply voltage (the same voltage as at the supply connector of CDA70).
Due to the loading of DSR output by a 100 ohm resistor to the earth, the supply voltage
on the output drops to 2V. CDA70 recognises the connection of the service cable and initiates
the communication on this user interface using the ARNEP protocol with defined
communication parameters. It is forbidden for user applications to load the output so that the